What type of fuel do aircraft use?
Aircraft use different fuels according to engine type. Most turbine aircraft burn kerosene-based jet fuel, usually Jet A or Jet A-1, while spark-ignition piston aircraft commonly use aviation gasoline, usually 100LL. Approved designs may instead use unleaded avgas, automotive petrol, jet fuel in compression-ignition engines, sustainable aviation fuel blends or electricity.
For Aviation & Real-World Flying, the quickest distinction is the engine rather than the aircraft's size or the presence of a propeller. A turboprop has a propeller but normally burns jet fuel; some modern piston engines also run on Jet A or Jet A-1.
Aircraft fuel types by engine
Engine design, certification and operating conditions determine the approved aircraft fuel.
| Aircraft or engine type | Typical fuel | Key point |
|---|---|---|
| Airliner or business-jet turbofan | Jet A or Jet A-1 | Kerosene-type turbine fuel |
| Turboprop or turbine helicopter | Jet A or Jet A-1 | A propeller or rotor does not imply avgas |
| Spark-ignition piston aircraft | 100LL avgas; approved unleaded avgas or automotive petrol in some aircraft | The exact grade must be approved for that engine and airframe |
| Compression-ignition piston aircraft | Usually Jet A or Jet A-1; sometimes a specified diesel grade | Often described as an aviation diesel engine |
| Military turbine aircraft | JP-5, JP-8 or another specified military grade | Civil jet fuel may be acceptable only under the aircraft's approved limits |
| Battery-electric aircraft | Electricity | No conventional liquid fuel is carried for propulsion |
A mistake we see constantly is treating “propeller aircraft” as a fuel category. The propeller only shows how thrust is produced; it does not reveal whether the engine is a spark-ignition piston engine, compression-ignition piston engine or gas turbine.
What fuel do commercial aircraft use?
Airliners and most business jets use Jet A or Jet A-1, both refined kerosene fuels made for turbine engines.
- Jet A is used primarily in the United States and has a freezing point no higher than −40°C.
- Jet A-1 is the more common international grade and has a lower maximum freezing point of −47°C, making it better suited to very cold high-altitude and long-range operations.
- Jet B is a more volatile, wide-cut petrol-and-kerosene fuel used only in limited cold-weather applications.
Jet fuel is loaded by volume but operational planning and cockpit indications commonly use mass in kilograms or pounds. Its density changes with temperature and batch, so a litre or gallon does not always represent the same mass. Our guide to understanding the A320's cockpit controls and displays helps connect those quantities with the fuel indications seen by a commercial flight crew.
What fuel do small propeller aircraft use?
Small propeller aircraft may use avgas or jet fuel, depending on the engine fitted.
Traditional spark-ignition piston engines commonly use 100LL avgas. It is normally dyed blue and contains tetraethyl lead; “LL” means low lead relative to older aviation grades, not lead-free. Its aviation performance rating is also not directly equivalent to the RON or AKI number displayed on a roadside petrol pump.
Some certified engines can use an approved unleaded avgas grade. Automotive petrol, often called mogas in aviation, is permitted only where the aircraft's type approval, supplemental approval or engine documentation specifically allows it. Vapour pressure, ethanol content, octane rating and fuel-system materials all matter.
Compression-ignition aviation engines often burn Jet A or Jet A-1, partly because those fuels are widely available at airports. Turboprops also use jet fuel even though they drive a propeller. For a simulated piston-aircraft example, the FS2004 GA8 panel with fuel-flow and consumption indications shows the sort of information pilots monitor during operation.
Are jet fuel and avgas interchangeable?
No, jet fuel and avgas are not interchangeable unless the aircraft's approved documentation explicitly permits the alternate grade.
- Jet fuel in a spark-ignition avgas engine can reduce anti-knock performance and cause detonation, power loss or engine failure.
- Avgas in a turbine can breach operating limitations and leave damaging lead deposits. A few turbine manuals allow limited emergency avgas use, but that is not general permission to substitute it.
- Road petrol and road diesel must not be used merely because an engine appears mechanically capable of burning them.
Nozzle shape, fuel colour or an informal assurance from the supplier is enough on its own. Fuel can be contaminated, mixed or placed in the wrong storage equipment.
How do pilots confirm the correct aircraft fuel?
Pilots confirm the required grade from approved aircraft documentation and then verify that the delivered fuel matches it.
- Check the limitations: read the aircraft flight manual, pilot's operating handbook, cockpit placards and any approved engine or fuel-system supplements.
- Specify the full grade: request Jet A, Jet A-1, 100LL or the exact approved alternative rather than asking only for “jet fuel” or “avgas”.
- Monitor the fuelling: compare the bowser or pump label, delivery paperwork and quantity with the order.
- Inspect samples: follow the aircraft's approved pre-flight procedure to check for water, sediment, contamination and signs of the wrong fuel. Colour can support the check but must not be the sole test.
- Stop if uncertain: do not start or fly the aircraft until the fuel identity has been established and any contamination has been dealt with by qualified personnel.
Can sustainable aviation fuel replace Jet A?
Certified sustainable aviation fuel can replace part of conventional jet fuel when it is produced, blended and released under an approved aviation-fuel specification.
SAF is not raw vegetable oil or one universal product. Different production pathways have different permitted blend limits; after blending and certification, the finished fuel is designed to work as a drop-in Jet A or Jet A-1 fuel without aircraft modification. Its environmental benefit concerns lifecycle emissions, which vary by feedstock and production method—it does not make combustion emissions disappear.
Hydrogen and battery-electric propulsion are separate technologies rather than grades of jet fuel. They require purpose-designed aircraft, storage and airport infrastructure, so they cannot be poured into an existing aeroplane as substitutes.
Does fuel type matter in flight simulators?
Fuel type matters in a simulator only to the extent that the selected aircraft models its fuel and engine systems.
Many simulators let users load a generic fuel quantity while the aircraft model assumes the correct grade. The more immediate causes of a failed start are usually an incorrect tank selector, closed fuel valve, mixture or condition lever at cut-off, or fuel pumps left off. Our FSX cold-and-dark starting walkthrough explains these simulated controls, but simulator procedures must never replace an approved real-aircraft checklist.